Monthly Archives: September 2018

Wild weather in the run up to the autumnal equinox was frequently a staple of the Septembers of my childhood but it has been absent in recent years.

Since 2013 I have been recording the ‘wind run’ data on my AWS, a stat generated by the amount of times the anemometer spins.

The results show there has been nearly two-and-a-half times more wind than the 5-year average.

Stormy weather over the equinox is one of the less frequent recurring singularities. The meteorologist Philip Eden a few years ago noted that ‘Mid-September storms’ during the period of 17th to 24th September had a frequency of 60 per cent.

Like this:

Street trees around Wanstead and the surrounding area have been disappearing at an alarming rate over the last few years. But it is not just the council’s technical policy of removing mature specimens that is to blame.

Changing rainfall patterns and poor husbandry have both contributed to the loss of some of the magnificent trees that once graced our roads and avenues.

Google images

Google images

A huge horse chestnut that once stood outside Wanstead High School first showed signs of distress in 2011. By 2017 it was completely dead and has since been chopped down.

Google images

Google images

One of the large limes on St Mary’s Avenue was a picture of health in 2015 but within two years it was completely dead and has also since been chopped down.

Google images

A huge old beech in the front garden of a property in Blake Hall Road was showing signs of distress in 2017 and came crashing down in 60mph winds from Storm Fion in January 2018.

Google images

Google images

Yet another huge old beech that stood proud in a front garden of St Mary’s Avenue has been dying since 2012. The second image reveals very thin foliage in summer 2017. The tree was chopped down a couple of weeks ago as it was clearly dead and posed an obvious safety risk, given what happened to the beech in Blake Hall Road in January this year.

Google images

Google images

The mature trees of Christchurch Green took a real hammering during the St Jude Storm in October 2013, among those lost were three gorgeous old limes. New trees have been planted but they will take decades to match the size of those lost.

Of course the loss of these trees and other could be attributed to bad luck and coincidence that many are reaching the end of their lives at the same time.

As a country we get a bit hung up on cutting trees down – in the near continent they are much more pragmatic and proactive through planning over a period of years in getting trees in the ground. So that when trees do die there’s not such a huge gap left in roads and parks.

On saying this there also needs to be more joined up thinking by councils in terms of looking after the existing tree stock. Far too many trees suffer because contractors are inconsistent with road and pavement repairs. Ideally the base of trees should have space for mulch to be applied but, too often, Tarmac is applied right up to the base.

Have you noticed mature trees dying suddenly recently? Please reply to this blog and I will add them.

While putting together my September extremes blog I noticed that the month was marked by some big rainfall episodes. On a national scale TORRO statistics show that a south-east climate station holds the daily record for September – unusual in that every other month is dominated by stations in the north and west of Britain.

Further analysis of local data since 1959 shows how September has slowly evolved from being dominated by autumnal to summery weather. The wettest period, from the mid Sixties to the mid Seventies, saw 42 per cent of highest daily rainfall events recorded.

Two of these events, in 1968 and 1973, are well noted and appear in RMET’s Weather magazine.

1968

In Wanstead, between 14th and 15th September, a total of 58.4mm fell, a large total though far less than elsewhere.

Noon Sept 15th 1968

Noon Sept 16th 1968

The rain became torrential overnight in southeast England and continued through most of the 15th. Rainfall totals ranged from three inches in the London area and nearly four inches in southern Essex to approach the quite abnormal level of nearly seven and a half inches in parts of Kent during the 14th/15th.

The area of greatest precipitation was near the Kent, Surrey and Sussex border where violent downpours in the 12 to 15 hour period from midnight on Saturday to the early afternoon of Sunday 15th led to widespread and disastrous flooding. The heavier rain area moved north and east during the night of 15th/16th and Gorleston recorded.

The highest accepted two-day falls were 201mm at two rain gauges at Tilbury
and Stifford in Essex, and a similar fall north of Petworth in Sussex. The highest ‘rainday’
totals (i.e. nominally 0900–0900 GMT) listed in British Rainfall 1968 were 129 mm at
Bromley and 125 mm at South Godstone sewage works in Kent, both on 15
September.

This exceptional event was described by Bleasdale (1974), Salter and
Richards (1974) and Jackson (1977) and the map below (Fig. 1) is taken from Bleasdale’s
paper in British Rainfall 1968 (p. 231). In all, some 575 km2 received more than 150 mm
in 48 hours.

1973

In Wanstead, on 20th, a total of 55.4mm fell, the largest daily total recorded in September. Again it was far less than elsewhere.

There were notable falls of rain in London, Surrey, West and East Sussex, and particularly Kent. At Manston, near Margate, 172 mm fell in 18 hours 40 minutes commencing 1710 GMT; at nearby West Stourmouth 190.7 mm fell in the rainfall day i.e. the 24 hours commencing 0900 GMT on 20 September (source: Met Office internal list of heavy falls of rainfall in short periods in the United Kingdom during the year 1973; Rainfall/heavy falls section listing, available in manuscript/computer printout form in Met Office archives).

The future

Big September rainfall events seem to be becoming rarer in our part of the UK, the last was in 2014, on the day of the Scottish referendum, though this was convective rather than frontal rainfall.

The outlook for the rest of this month suggests yet another absence of a large rainfall event. The ingredients for large rainfall totals in the south-east – blocking high to the north with slow moving low pressure over Brittany – look unlikely to form during the remainder of the month. We probably will see rain but any fronts are likely to move through quickly, with typical totals being around 5mm.

The answer is around 1993. A look back at mean temperature and rainfall statistics for east London over the past hundred years reveals that the ninth month has, since that date, slowly become warmer and drier.

Putting all the arguments of meteorological and astronomical summer aside, many people of a certain age regard September as an autumnal month, but as recent years have shown it can very often be an extension of summer; September 2016 was the second warmest on record in the local area, warmer than many previous summer months!

Looking back even further, over the past 100 years, the September mean has trended upward, though many peaks and troughs reveal how the month has ebbed and flowed from being summery to autumnal.

The prognosis to the end of this month suggests that air pressure will be anomalously high – so the pattern in the south-east for settled, summery weather in September doesn’t look like ending any time soon.

The September mean trend has crept generally upward.A look at rainfall back over the last 100 years shows that wet Septembers have been on a general decline since 1994.

Like this:

Four months on from an amazing ski tour I was back in the Swiss Alps in August, this time for a week of mountaineering and rock climbing.

The (mostly) white wonderland of April had transformed into the deep green of summer in the valley, the temperature on my arrival in Visp was a hot 30C. Waiting patiently was my guide, Davide, and we were soon on our way to the cooler climes of Saas Grund, little sister to Saas Fee – though with scenery as, if not more, spectacular.

The glacier leading up to the 4,017m Weissmies stops abruptly around 3,000m

Day 1: Jagihorn from Hohsaas hut

Mountain sickness saw me abandon any attempt of climbing the Weissmeis. Though sleeping at the the Hohsaas hut was intended to help me acclimatize to the altitude I think the 3,100m elevation was simply too much for my system to handle. It is hard to put into words the symptoms; imagine your worst-ever hangover and multiply it by five.

The Hohsaas hut, left, and cable car

Anyone can get sudden altitude sickness, even top athletes. After an awful night I was ready to descend back to Saas Grund but was soon sent back to bed with a painkiller. Two hours later I was just about fit to set off and was soon descending down the valley to climb the 3,200m Jegihorn in the far distance. I felt a pang of disappointment as I glanced over my shoulder at the magnificent Weissmeis; the purpose of the week was to get as much glacier mountaineering as possible.

The Jegihorn can be seen in the distance

As we traversed over the scree and across gurgling streams however, the beauty made me forget my disappointment. The sheer magnificence of the Jegihorn soon became apparent, too. It reminded me of Tryfan in Snowdonia, only this was three times the size.

The route up soon forked – it was either the ‘easy’ way up or via ferrata, a series of steep drop offs, grab handles, steps and precarious looking ladders allowing access up sheer cliffs. After a couple of hours progress to the peak proper becomes a choice of climbing down and up or this suspension bridge that is like something out of the film Cliffhanger.

This suspension bridge, high above a ravine, saves the pain of walking down and up to the summit proper.Like something out of the film Cliffhanger

After the bridge it is a further scramble up steep ledges and narrow gullies for the remaining couple of hundred metres to the summit.

The summit of the Jegihorn with Saas Fee in the far distanceThe 3,206m Jegihorn using the via ferrata route up

With every summit comes a descent, the part I always find the hardest because of the strain on the knees. But the trek back to the bottom of the Hohsaas cableway presented plenty of scenery.

A solitary cloud hangs above a aquamarine mountain lakeThe rugged and harsh glacial landscape, shaped over millions of yearsThe landscape on the way down from the Jegihorn shows all the signs of movement that comes with timeI saw about 5 marmottes on the descent. You can see one under the rock if you look closely

Like this:

I often look at the excellent webcams of London site to help me decipher cloud types and amounts for my 9am GMT observation. This evening I discovered that the timelapse of the last 24 hours included a very interesting white light floating past the Shard.

At limited resolution it is difficult to see what the object is. My suspicions that a UFO had been captured were quickly shot down with the help of Twitter including the excellent @VirtualAstro

In terms of climatology September maxima, considering the 1981-2010 average, shows a slight decrease through the month, though around the 1st and the 22nd there is often a spike. This would reflect the September singularities; early September warmth occurs in 82 per cent of years while the ‘Old Wives Summer’ has a 64 per cent probability.

The average rainfall graphic shows that downpour amounts are variable through the month. A tendency for dry weather to the 8th prevails before the trend increases, the wettest days usually 13th and 19th.

August was a big let down in a summer that saw the mean temperature nationally match the UK’s best-ever summers.

Summer maxima took a real dip during the first week of August

The mean temperature finished 18.9C, 0.7C above average.

Some 69.5mm of rainfall was recorded, 139 per cent of the 1981-2010 average. Some 169 hours of sunshine were recorded, 87 per cent of average. Apart from being 1.5C warmer than average it was a carbon copy of last August.

Like this:

The results are in and statistics show that this summer was the second hottest in a local record going back to 1797. The mean temperature of 19.57C was 2.4C warmer than average, just six hundredths of a degree cooler than the summer of 2003.

A sustained period of heat that continued the theme of the hot late spring was enough to see a new entry into the hottest-ever list of heatwaves. But the hottest weather was over by the end of July, August being very disappointing compared with the first two months of summer.

It was also the driest summer for 15 years. Just 87mm were recorded, that’s 60 per cent of average and just 7mm wetter than the historic summer of 2003, the year the UK’s highest temperature record was set.

It was the sunniest summer for 5 years: 663 hours of sunshine were recorded, over 100 hours less than 1976, the 24th sunniest summer since 1881.

Sunsets

Sunset on 31st looking across Wanstead Flats. July was a classic summer month for weather

It was a month with some amazing sunsets. This one, on April 30th, happened just as the sky cleared before dusk

A stunning example of sunlight illuminating the underside of cloud at sunset was seen mid-month

sunset overlooking Wanstead Flats 2nd August

Sunset on Wanstead Flats

Sunset Southwark Bridge

Typical April days of sunshine and showers were in short supply. There were some stunning sunsets, including this one on the 30th

I took this yesterday evening. Windless, still and humid at ground level it was fascinating to look skyward and see the multi-level cloud continue to build into strange shapes, illuminated from below by the setting sun. A wonderful weekend for cloudspotting.

With the sun lower in the sky at this time of year there’s often a great opportunity for a decent sunset

Satellite images

Ophelia

Both the 2013 storm, left, and the 1987 storm followed a similar track as shown on these satellite pictures

On 25th a perfect curl could be seen on a depression centred off the west coast of Irleland. The rain associated with this low pressure brought the month’s highest daily rainfall total: 23.4mm (the system bringing 27.5mm) – a thoroughly miserable Bank Holiday Monday where it rained ALL day, from 6am until 9.30pm. It was yet another example of how much even frontal rainfall can vary over a small area.

This satellite picture taken on December 27th, 2014, shows the LP clearing through to leave us in clear, deep cold air